Washington: Children with juvenile idiopathic arthritis (JIA) are four times likelier to have cancer than those without the disease, researchers have revealed.
The findings suggest JIA treatment, such as tumor necrosis factor (TNF) inhibitors, does not necessarily explain the development of cancer in this pediatric population.
Children with JIA experience symptoms similar to adults with arthritis including joint pain, swelling, tenderness and stiffness.
JIA is a general term used to describe the various chronic arthritis diseases in children.
One of the drug types used to treat childhood and adult arthritis, along with a number of other rheumatic conditions, is TNF inhibitors.
Studies have reported that more than 600,000 people worldwide have received anti-TNF therapy since their introduction 15 years ago. However, possible cancer risk has been associated with treatment, prompting the U.S. Food and Drug Administration (FDA) to place “black box” warnings of the potential malignancy risk on TNF inhibitors labels.
In the present study Dr. Timothy Beukelman from the University of Alabama at Birmingham and colleagues conducted one of the largest investigations into the rates of incident malignancy among JIA pediatric patients relative to their treatment.
Using data from the U.S. Medicaid records from 2000 through 2005, researchers identified 7,812 children with JIA and two comparator groups without JIA; one group with asthma (652,234 children) and the second with attention-deficit hyperactivity disorder (ADHD; 321,821 children).
The team categorized patients’ treatment with methotrexate and TNF inhibitors as “ever” or “never” used, though many children with JIA did not receive either of these treatments during the study.
The research team did not have access to detailed medical records, and therefore categorized the identified incident malignancies as “possible,” “probable,” or “highly probable.”
The team determined that among all children with JIA compared to those without JIA, the incidence rate was 4.4 times higher for probable and highly probable malignancies.
Pediatric JIA patients treated with methotrexate without TNF inhibitors had a similarly increased incidence of cancer, which was 3.9 times higher than children without JIA. No probable or highly probable malignancies were identified in patients following any use of anti-TNF during the study period.
“While our findings show children with JIA have a higher incidence of cancer compared to peers without JIA, the greater frequency of malignancy does not appear to be necessarily associated with treatment, including use of TNF inhibitors,” Dr. Beukelman stated.
“This highlights the critical importance of appropriate comparator groups when evaluating the safety of new medications. Further confirmation of our findings with large-scale and long-term investigation of the association between cancer and JIA, and its treatment is needed,” he added.
The findings are available in Arthritis and Rheumatism, a journal published by Wiley-Blackwell on behalf of the American College of Rheumatology.